Face mask for protection against dust and the like



April 8, 1952 MacLEAN 2,591,953

FACE MASK FOR PROTECTION AGAINST DUST AND THE LIKE Filed March 25, 1949Inventor:

Attorneys:

Patented Apr. 8, 1952 FACE MASK FOR PROTECTION AGAINST DUST AND THE LIKEThomas Traill MacLean, London, England, assignor to Anglo-Iranian OilCompany Limited,

London, England, a B

ration ritish joint-stock corpo I Application March 23, 1949, Serial No.82,933 In Great Britain April .16, 1948 The invention relates to facemasks for protection against dust and other finely divided solidparticles suspended in the air.

The invention has among its objects to provide A,

a form of dust mask which obviates the need for valves. It is anotherobject of the invention to I provide a mask that is easy and comfortableto wear and that ofiers no obstruction to the sight. Yet another objectof the invention is to provide a mask wherein the efiiciency of thefiltering eifect of the mask may be varied to adapt the mask for use inatmospheres having varying dust contents and in which the filterelements may easily be removed for cleaning, and if necessary,replacement. It is still another object of the invention to provide amask having filter elements that can be easily cleaned and sterilised.

According to the invention, a face-mask for protection against dust orother finely divided solid particles, comprises a face-piece adapted tocover the nose and mouth and formed at its lowermost point with anaperture in which is located a perforated screen inclined to the generaldirection in which air passes into the mask, whereby when air havingsolid particles suspended thereinis drawn into the mask by in- 4 Claims.CL 128-146) 2 Figure l is a perspective view of the complete mask, v

Figure 2 is a perspective view of a filter screen for use in the mask,and

Figure 3 is a cross-section through the lower portion of the maskshowing the arrangement of the screens therein.

The mask comprises a face-piece Ill which is formed with an upperopening I I shaped to make a close fit around the nose and mouth, a beador rim I2 being conveniently formed around said opening. The face-piecemay be madeof any suitable material but is conveniently made of softrubber. A strap I3 is secured to the facepiece for supporting the maskfrom the head,

, said strap being permanently secured at one end to the face-piece andbeing detachably secured thereto at the other end by means of anysuitable releasable fastening such as a press stud fastener l4. s

The lower portion I5 of the face-piece is formed to a rectangularsection to accommodate a number of filter screens l6 one of which isillustrated in Figure 2. The screens are formed of any suitableperforate material, such as metal halation, the solid particles are heldback by v the screen, the process being assisted by the wetting actionof the exhaled air which also prevents an undue accumulation ofparticles on the screen.

The screen is advantageously of inverted V- section and a number of suchV-section screens may be nested one within the other so that air drawnthrough them will change direction a number of times thereby causingsolid particles to lose velocity and to settle out on or adhere to thescreens. The number of screens used regulates the degree of filteringachieved.

The inverted V-section screens may advantageously be formed with a lowerportion with parallel sides around which is secured a head or band,whereby the screens may be nested one within the other with the beads orhands in contact and with the inverted V-section portions of the screensspaced away from each other.

The screens are advantageously made of metal gauze. since such screenscan be readily removed and cleaned, but they may also be made of finermesh material, such as fabric, where finer particles of dust require tobe removed from the air stream.

7 One embodiment of the invention will now be described by way ofexample with reference to the accompanying drawings wherein:

gauze, and as shown are in the form of triangular prisms having an openbase, inwardly sloping ends Hand quadrilateral sides IS. 'The screensare formed with a parallel-sided lower portion l9 around which issecured a metallic band 20. Said bands provide a convenient means ofpositioning and spacing the filter screens from each other when they arenested one within the other, as shown more particularly in Figure 3.-;It will be understood that the bands20 need not f extendcompletelyaround the screens to perform their spacing function but it isconvenient that a they should do so since the strength and rigidity ofthe screen is thereby increased. The dimensions of the face-piece and ofthe screens are such that the rectangular section portion [5 of theface-piece requires to be distended in order to insert the screenstherein whereby the screens are firmly held in position. The portion l5of the face-piece may be formed with an inwardly directed bead 2| aroundits lower edge in order to position and retain the filter screens.

When air is inhaled through the screen assembly, it is caused to scrubthe surface of the screens will settle out on or adhere to the screens.The "majority of particles adhere to the under surfacesof the screensand the exhalation of moist air will remove suflicient of the adheringparticles to prevent such heavy accumulation as would restrictbreathing.

It will be understood that both inhalation and exhalation take placethrough the screen assembly, no separate ekhalation valve beingprovided.

I claim:

1. A face mask for protection against dust or other finely divided solidparticles, which comprises a face-piece adapted to cover the nose andmouth and formed at its lowermost point with an aperture in which arelocated a plurality of inverted V-section screens nested one within theother, said screens being in the form of triangular prisms having anopen base and inwardly sloping ends, whereby when air having solidparticles suspended therein is drawn into the mask by inhalation, saidsolid particles are held back by said screens.

2. .A face mask according to claim 1, wherein said screens are formedwith a lower portion with opposed pairs of parallel slides around whichis secured a band, whereby the screens are nested one within the otherwith the bands superimposed and in contact and with the invertedV-section portions of the screens spaced away from and parallel witheach other.

3. A face mask according to claim 2 wherein said face-piece is formedwith a lower portion of rectangular section to accommodate theparallelsided portions of the screens.

4. A face mask according to claim 3 wherein said portion of rectangularsection is formed with an inwardly directed locating and retaining beadaround its lower edge.

THOMAS TRAILL MACLEAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

